As materials for related art stretch seal, paraffin resin, vinylidene chloride resin, polyethylene resin, and the like have been used. Paraffin resin has good extensibility and moisture resistance but cracking or fracture may occur due to an organic solvent or the vapor thereof. Vinylidene chloride resin generally has chemical resistance but is soft and films thereof are easily stuck to each other and are easily torn, and therefore, there have been difficulties in use, such that it is difficult to find a take-out slot.
Moreover, the chemical resistance of vinylidene chloride resin to an ether-based solvent and a hydrocarbon-based solvent is low. Furthermore, since chlorine is contained, careful handling of the vinylidene chloride resin is required for incineration. Polyethylene resin has low adhesiveness to various containers, and therefore polyethylene has been limited in use.
Vinylidene chloride has high chemical resistance but low breaking strength. Moreover, vinylidene chloride has low durability to an ether-based solvent and a hydrocarbon-based solvent. Furthermore, since vinylidene chloride contains chlorine, there has been a possibility such that harmful gas is generated when vinylidene chloride is incinerated.
In NPL 1, the chemical resistance of vinylidene chloride has not been clarified.